Further studies on the relationship of a rhabdomyosarcoma virus to muscle tissue

Abstract

The pathogenesis of a rhabdomyosarcoma virus isolate was studied in a total of 300 newborn BALB/c mice, 11 different routes of inoculation being used. The latent periods, or time in days to palpable tumor, varied over a wide range among the inoculated groups. The growth of the tumor was very rapid in the muscle tissue. Regardless of the route of inoculation, the neoplasms arose from the adjacent muscle tissue attaching to and proliferating into the different organs and from their surfaces. Secondary tumor nodules were also observed in different areas of muscle tissue demonstrating the affinity of this virus to muscle tissue. Exceptions were found in some of the intrasplenically and intramyocardially inoculated mice where primary tumor nodules were found within these organs. Histologically the tumor cells were less differentiated toward myocytes than those described in a previous study.It is suggested that this host response is a reflection of the high initiating virus dose employed.Increase in spleen and liver weights and decrease in hematocrit values correlated closely to the extent of tumor development.